1. Field
The present disclosure relates to devices and methods for resisting the compromise of locks, and more particularly pertains to a new system for obstructing movement of pins in a lock when a sidebar of the lock engages the pins for protecting high security locks against compromise.
2. Description of the Prior Art
Locks employing pin tumblers have long been utilized for providing security for buildings such as homes and businesses. Pin tumbler locks include a plug that is inserted into a shell, and the plug may be rotated with respect to the shell when the correct key for the lock is used on the lock. The plug includes a keyway for removably receiving the blade of the key. The blade of the key engages a plurality of pin tumblers arranged along the keyway to contact the blade of the key at different and discrete locations. The pin tumblers each comprise a lower or bottom pin (sometimes referred to a key pin) that contacts the key blade, and an upper or top pin (sometimes referred to as a driver pin) that is pushed or lifted upwardly by the bottom pin. The top and bottom pins are positioned in a bore that extends from the keyway in the plug through and into the shell, and in the locked or vertical position of the plug the bores in the plug are substantially aligned with the bores in the shell.
The blade of the key is bitted, or cut, at a plurality of positions along the blade and in a unique pattern that is adapted to the configuration of the pin tumblers of that lock. The height of the bottom and top pins of each pin tumbler varies from tumbler to tumbler, so that the bitting for one position may not work for another position. The bitting at each position is such that the bottom pin is raised in the bore until the juncture between the bottom pin and the top pin lies in a shear line, which is located at the point where the bore in the plug and the bore in the shell meet. When the proper key is inserted, the junctures between the top and bottom pins are aligned with the shear line between the plug and shell, and the plug will freely rotate with respect to the shell. In other words, a key with the proper bitting places the top pins completely in the shell and the bottom pins completely in the plug, and the plug is able to rotate in this condition. The rotation of the plug may actuate a mechanism that moves, for example, a deadbolt or door latch.
High security locks are utilized to present an extremely pick resistant cylinder for commercial, government, and military applications where a high level of security against covert entry is required. Certain types of high security locks are known to utilize pin tumblers in which the bottom pins are both lifted and rotated by the interaction of the bitting of the key with the pin tumblers. In such instance a vertical aspect of the bitting of the key blade elevates the upper surface of the bottom pins to the shear line while an angular portion of the bitting rotates the pin to a particular angle.
One known high security lock structure is available from Medeco of Salem, Va., and aspects of various Medeco locks are disclosed, for example, in U.S. Pat. No. 3,499,303 and U.S. Pat. No. 3,722,240 (the disclosure of each of these patents being incorporated herein by reference in their respective entireties). In these locks, one (or more) of three available angles is employed for the angular bitting to cause the pin to rotate with respect to the bore. For example, in some of these types of locks, the pin may be rotated by the angular bitting of key to a position substantially parallel to a central axis extending substantially transverse of the blade, a position rotated twenty degrees left of the central axis or a position rotated twenty degrees right of the central axis. The rotation of the pins into their proper rotational position permits gates on the pins to be aligned so that legs on a sidebar are able to move into the gates and the sidebar can in turn be moved from a position that extends out of the plug and into the shell to a position that is retracted into the plug, thus allowing the plug to rotate with respect to the shell. Some variations of this lock, referred to as a “biaxial” design as is disclosed for example in U.S. Pat. No. 4,635,455, positional bitting is employed in which the contact surface of each pin may be located in one of two positions within the respective plug bore—either before or after the center line of the plug bore. The combination of the three rotational bittings, two positional bittings and several vertical bittings are believed to offer maximum resistance against all forms of covert entry by providing more than 46,000 sidebar codes in addition to approximately 3,000,000 theoretical combinations of vertical bitting, angular bitting, and positional bitting.
The introduction of the sidebar to high security locks provided an extremely high resistance to almost all forms of picking and decoding by locks so equipped. As a result, lock designs that employ the combination of the pin tumblers and a sidebar, such as the Medeco lock, have been considered to be the most difficult cylinders to compromise by covert means, and have been certified as meeting the criteria for UL 437 and ANSI 156.30 for high security locks. In part this certification is due to the unique sidebar design that provides a high resistance to most methods of picking and decoding. Although several tools are known to have been developed to attempt to bypass locks including the sidebar, these tools have all required a high skill level to utilize and often were not considered to be completely effective.
In 2004, the technique of “bumping” attracted worldwide attention as a “new” method of bypass for almost all of the conventional pin tumbler lock designs. This practice was apparently patented in the United Kingdom in 1925 (United Kingdom Patent No. 251,810), and had been known by locksmiths for many years. Bumping involves the use of a specially cut key that is rapidly and forcefully moved in the keyway of the lock to cause the pin tumblers to jump in the bores, and the bottom and top pins to momentarily separate, so that when rotational torque is applied to the plug, it may cause the plug to rotate when the separation between the top and bottom pins align with the shear line. This technique has placed almost all pin tumbler cylinders at risk. However, locks that employed sidebar technology were heretofore believed to be immune to being compromised by bumping. In fact, manufacturers of locks employing sidebar technology have touted this perceived immunity to the bumping technique in sales information, stating that the locks are “bump proof.”
The high security locks upon which the techniques and devices of the present disclosure are effective typically implement two separate yet integrated locking systems. The first system is the conventional pin tumbler system in which a properly bitted key positions the split or juncture between the top and bottom pins with the shear line between the plug and shell.
The second system is the sidebar system in which a properly bitted key rotates the bottom pins to align side channels or gates in the pins such that the gates permit the side bar to move inwardly with respect to the plug and out of engagement with the shell. Correct alignment by rotation of each bottom pin tumbler to one of three angle positions of the key causes a gate within each pin to be aligned with the corresponding protruding leg of the sidebar. Only when the gates in all of the pins are horizontally and vertically aligned can the sidebar be retracted into the plug to allow turning by the key.
Thus, only the combination of the alignment of the split or juncture of the pins with the shear line and the ability of the side bar to move inwardly allows rotation of the plug with respect to the shell. Both of these systems must be properly aligned at the same time before the plug is allowed to rotate within the shell.
Some high security locks incorporate a third system for key control and security. The third system is a slider, which is a movable component controlled by a protrusion on the side of the correctly configured key which causes the slider to move laterally toward the rear of the keyway as the key is inserted into the keyway in order to allow (or block) the inward movement of the primary sidebar. The technology employed in such as system is disclosed, for example, in U.S. Pat. No. 6,945,082, which is incorporated herein by reference in its entirety. There are a number of different positions to which the slider can be moved by a step on a change key, a master key, or a combination thereof. The slider mechanism thus presents another security level to overcome if the lock is to be bypassed.
So-called tryout keys have been known for at least seventy-five years by locksmiths and were first developed to open motor vehicle locks by exploiting vertical tolerances between the depth increments used in a wafer lock. Basically, the tryout key is bitted at each wafer position to a depth that is halfway between two adjacent depth increments for that position, which is within the manufacturing tolerance of each of those depth increments, so that bitting the key to the halfway increment will work if either of the adjacent bit increments is correct for that position of the keyway. A total of 64 keys, for example, could open 4096 different General Motors sidebar locks in the United States in the 1960s. This comprised every possible combination of a six wafer lock with four depth increments for each wafer. Tryout keys allowed locksmiths to carry relatively few keys to open all cars.
The conventional methods of manipulating individual tumblers within a high security lock, such as the Medeco lock described above, is extremely difficult using any form of conventional pick. The lock employs security pins, paracentric keyways, and a sidebar as a secondary locking system. Newer lock designs add another layer of security by blocking the action of the sidebar unless a slider is moved to the correct position by the key, making picking of the lock by conventional means even more difficult.
The primary deterrent to picking these high security locks is the aforementioned need to rotate each bottom pin to one of three precise angles. Each lock or group of locks will have a unique sidebar code, which is the composite group of angled cuts for each pin.
Additionally, some high security locks such as the Medeco locks employ secondary channels or false gates on each pin to provide a false indication as to when the pins are in the correct rotational position to permit the sidebar fence to properly engage the pins. For an even higher level of security, the Medeco locks may employ a special bottom pin in one or more positions along the keyway that has a vertical sidebar channel that is precisely the dimension of the leg of the protruding fence. This pin, identified as an ARX by Medeco, renders all forms of manipulation almost impossible. In order to successfully bypass the security features of a high security lock, such as the Medeco Biaxial lock, two things must simultaneously occur: the bottom pins must be raised to the shear line and the pins must be properly rotated to allow the sidebar to retract. In some of the newer lock, a slider must also be positioned to allow the proper interaction of the slider fence with the gates in the pins.
Even if the precise sidebar code is known for the target lock it is virtually impossible to utilize that information during picking because of the difficulty in rotating each pin to the correct position. Picking difficulty is compounded by the use of at least two security pins which provide a false indication when they are at the shear line. The false vertical channels on each bottom pin also add to the difficulty. Finally, the blocking action of the sidebar can prevent the setting of pins at the shear line, thus effectively preventing the lock from being feel-picked.
In these respects, the system for obstructing movement of pins in a lock when a sidebar of the lock engages the pins according to the present disclosure substantially departs from the conventional concepts and designs of the prior art devices, and in so doing provides devices and methods primarily developed for the purpose of protecting high security locks against compromise.